This section is intended to provide background information to facilitate a better understanding of the various aspects of the described embodiments. Accordingly, it should be understood that these statements are to be read in this light and not as admissions of prior art.
Many waters contain alkaline earth metal cations, such as barium, strontium, calcium, magnesium, and anions, such as sulfate, bicarbonate, carbonate, phosphate and fluoride. Precipitates can form when combinations of these anions and cations are present in concentrations which exceed the solubility product of a scale compound. For example, when the concentrations of barium and sulfate ions exceed the solubility product of barium sulfate, a solid phase of barium sulfate will form as a precipitate. Solubility products are exceeded for various reasons, such as evaporation of the water phase; changes in the pH, pressure, or temperature; and the introduction of additional ions which can form insoluble compounds with the ions already present in the solution.
As these reaction products precipitate on surfaces of water-carrying or water-containing systems, they form adherent deposits or scale. Scale can interfere with fluid flow, particularly in production systems for oil and gas. As an example, when formation fluid with brine is brought to the surface, scale can deposit inside production pipe and downhole tools, such as submersible pumps, constricting the production flow.